Automatic arc welding apparatus



April 1942- v. 'J. CHAPMAN 2,280,627

AUTOMATIC ARC WELDING APPARATUS Filed Aug. 9, 1940 S Sheets-Sheet l Z!Pl 9.1.

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His Attorney April 21, 1942. v. .1. CHAPMAN AUTOMATIC ARC WELDINGAPPARATUS Filed Aug. 9, 1940 3 Sheets-Sheet 2 'lloc it! Inventor: VerniJ. Chapman,

His Attorney April. 21, 1942.

V. J. CHAPMAN AUTOMATIC ARC. WELDING APPARATUS 3 Sheets-Sheet 5 FiledAug. 9, 1940 verni J. Cgapman, b .W. y His.Attorne Patented Apr. 21,1942 AUTOMATIC ARC WELDING APPARATUS Verni J. Chapman, Schenectady, N.Y., assignor to General Electric Company, a corporation of New YorkApplication August 9, 1940, Serial No. 351,995

10 Claims.

My invention relates to automatic arc welding apparatus. 7

It is an object of my invention to provide means for supporting andtraversing a line of welding on work of irregular contour past apredetermined point of welding.

It is a further object of my invention to support the work to be weldedon a turntable so that the line of welding on the work is parallel toand in registry with a cam surface by means of which translation androtation is imparted to the turntable to traverse the line of welding onthe work relatively to the arcing terminal of an electrode located atthe point of welding.

It is also an object of my invention to provide an arrangement in whichthe tangential engagement between a wheel and the turntable cam surfacemay be shifted about the axis of rotation of the wheel to adjust thepoint of welding.

It is another object of my invention to provide mechanism which holdsthe work on the turntable and accommodates the rotary and trans latorymotions of the turntable and the same motions of the work supportedthereon.

Further objects of my invention will become apparent from the followingdescription of the arc welding apparatus illustrated in the accompanyingdrawings.

Fig. 1 of the drawings is a perspective view of an automatic arc weldingmachine embodying my invention; Fig. 2 is a diagrammatic view of itsheadstock mechanism for rotating and translating the turntable on whichthe work is supported and of its tailstock mechanism which clamps thework against this turntable and accommodates its rotary and translatorymovements; Fig. 3 is a detailed view of the turntable cam and the rollswhich engage and drive it; Fig. 4 is a detailed view of the constructionof the tailstock mechanism; Figs. 5, 6, 7, and 8 are detailed views ofthe electrode feeding attachment forming part of the machineillustrated; and Fig. 9 is a wiring diagram showing the arrangement ofapparatus employed for controlling the operation of this machine. y

In accordance with my invention the machine of the drawings embodies aheadstock mechanism for rotating and translating a turntable upon whichthe work is supported so that the line of welding thereon is traversedrelative to the arcing terminal of an electrode located against a guideforming part of the above referred to feeding attachment. It alsoembodies a tailstock mechanism which has a member guided into and out ofengagement with the work on the turntable and movable with the workduring the motions of translation and rotation imparted thereto by theturntable.

The machine shown in the drawings also embodies a stick electrodefeeding attachment of improved construction which forms the subjectmatter of my divisional application Serial No. 406,387 filed August 11,1941 for Arc welding apparatus.

This machine also embodies means which not only terminates each of aseries of welding operations capable of being performed with the samestick electrode after predetermiend lengths of the electrode have beenconsumed in these Welding operations, but which also automaticallyreturns the electrode holder of the electrode feeding attachment to itsloading position by suitably controlling its feeding means after thelast Welding operation has been terminated. This control apparatus formsthe subject matter of my divisional application Serial No. 406,388 filedAugust 11, 1941 for Arc welding apparatus.

Referring to Figs. 1 and 2 of the drawings, an electrode feedingattachment [0 is mounted on a welding head It and propelled by the feedrolls 12 of this welding head. The welding head is illustrated as havingthe construction disclosed and claimed in United States Letters Patent2,170,673, Jasper E. Anderson, granted August 22, 1939 and assigned tothe assignee of this invention. It is supported on a crank shaped arm (3which is mounted on a pillar l4 forming part of the welding machineframe. As illustrated in the drawings, this welding head is adjustableon arm I3 and this arm is adjustable on pillar I l so that the arcingterminal of the electrode i5 held and guided by the electrode feedingattachment 10 may be positioned at a desired point of welding over theWork.

The work 16 is supported on a turntable I! so that the line of welding18 thereon is parallel to and in register with a flanged cam 19 having aconfiguration corresponding to the line of welding. This cam is mountedon the side of the turntable opposite its work supporting surface. Thiswork surface or a member 20 mounted on the turntable and forming a partthereof is so shaped as to position the work with its line of weldingparallel to and in register with cam 19. The work illustrated in thedrawings is a float valve chamber formed of two shell-shaped halveswhich are initially assembled by spot welds between their flanged edgedportions which are to be are welded in order to complete the assembly.

Turntable I! is mounted for rotation and translation relative to thehead stock 2i of the welding machine. It is guided in its movement by aplurality of balls 22 held in ball races 23 which are supported on theend 24 of the head stock opposite thereto. It is supported through theagency of cam I9 on a feed roll 25 which is mounted on one end of ashaft 26 journaled in bearings located in the two ends 24 and 2'! of thehead stock of the machine. Shaft 23 and feed roll 25 are turned abouttheir longitudinal axes by travel motor 23 which is connected throughgears 29 to impart rotation thereto.

As shown in Figs. 2 and 3, cam I9 is held on feed roll 25 by a pressureroll 30 having a flanged edged portion 3| which enters a groove 32 inthe outside surface portion of cam l9. Pressure roll 30 is mounted forrotation about one end of a lever 33 whose other end is pivoted at 34 toa frame 35. This frame is mounted for rotation about shaft 25 and itsadjustment about this shaft causes roll 3| to swing in an are about theaxis of rotation of feed roll 25 as shown by the dotted lines in Fig. 3.Lever 33 is biased toward frame 35 by a spring clamp 36 mounted on theframe. This clamp is provided with an adjusting rod 3'! which extendsthrough a slot in the head stock of the machine and through a coverplate 38 for this slot. Its projecting end portion is provided with handwheels 45 for adjusting the pressure which the spring clamp exerts onlever 33 as well as for rotating and positioning frame 35 relatively tothe head stock of the machine. A slot 39 in end plate 24 of the headstock permits the movement of lever 33 resulting from this adjustment.

The rotational adjustment of pressure roll 30 about feed roll 25 shiftsthe point of tangential engagement of these rolls with cam I9 relativelyto the head stock 2| of the welding machine. Since the point of weldingis determined by and is opposite the point of engagement of rolls 25 and30 with cam IS, the adjustment thus provided makes it possible to shiftthe point of welding relative to the frame of the machine on which thewelding head is mounted. For example, in welding the float valve chamberillustrated, it was found desirable to weld in a down-sloping positionand the rolls 29 and 33 were so adjusted as to position the workrelatively to the head stock of the machine to accomplish this.

Welding current is supplied to the work through turntable i1, cam I9,feed roll 25, shaft 26 and brushes 4| from one terminal of a source ofsupply through conductor 42. The other terminal 43 of this source ofsupply is connected to the electrode holding portion of feedingattachment it.

The work holding surface of the turntable may be proportioned andarranged to provide a sub stantially airtight engagement with thesurface of the work part l resting thereagainst. If the chamber thusformed between the turntable and the work is connected with a vacuumline, atmospheric pressure may be employed for initially holding thework on the turntable. Such an arrangement has been illustrated in Fig.2 where the vacuum line 44 is connected through a valve 45 and a conduit46 to the chamber formed between the turntable and the work. The end ofconduit 46 may be provided with a ball and socket joint and the conduititself may be in part flexible as illustrated in order to accommodatethe rotation and translation of turntable ll relative to the frame ofthe machine on which valve 45 is supported.

A clamping pressure is applied to the work [6 through a tail stockmechanism diagrammatically illustrated at 41 in Fig. 2. This tail stockmechanism forms a part of the welding machine and is mounted on itsframe. A work engaging member 48 is moved to and from the work by themovement of a lever 49 pivoted at one end in a support 50 attached tothe frame of the machine. A piston rod 5| pivotally attached to a midportion of lever 49 constitutes in combination with the fluid operateddouble acting piston and cylinder 52 means for moving lever 49 towardand away from the work about its pivotal support in member 50. Fluidunder pressure is supplied to and exhausted from opposite ends ofcylinder 52 through a valve 53 which is properly positioned to obtainthe desired movement.

As shown in Fig. 4, the upper end of lever 49 is connected through alink 54 to a supporting member 55 for the work engaging member 48.Member 55 is tubular and mounted for sliding movement toward and awayfrom the work in tubular guide 56 which is attached to the frame of thewelding machine. Work engaging member 48 is also tubular in shape andhas a work engaging cup 51 at one end thereof. Its other end is providedwith a stud 58 threaded into the end there of. This stud forms a supportfor a round spring rod 59 whose outer end extends through a roundopening in a block 60 mounted within support member 55. A ball bearing6| is located on stud 58 and held in place thereon by a nut 62 threadedonto the outer end portion of stud 58. The outer race of this ballbearing is held against an in ternal shoulder in the end of supportmember 55 by a collar 63 which is attached to the inside surface of theend of member 55 by screws 64. This race has a spherical ball engagingsurface so that the connection between the work engaging member 48 andits support member 55 forms a ball and socket joint of rotation whichpermits the work engaging member 48 to accommodate itself to therotational and translational movement imparted to the work I6 by theturntable H on which it is supported. The opening between the workengaging member 48 and its support member 55 is closed by a felt washer65 held in place by a collar 66 mounted on and attached to member 48.

The tail stock mechanism is insulated from the frame of the machine sothat welding current must be supplied to the work [6 by way of turntableH on which it is supported. By thus confining the direction in whichwelding current is supplied to the work, better welding conditions areestablished.

The stick electrode feeding attachment, which positions the arcingterminal of electrode l5 over the desired line of welding, is bestillustrated in Figs. 5, 6, '7, and 8. This attachment forms the subjectmatter of my above referred to divisional application Serial No.406,387. It comprises an electrode guide 61 mounted on the lower end ofa member 68 whose upper end is attached to and electrically insulatedfrom one end of an angular frame 59 whose other end is attached to thewelding head II. It also comprises a holder 15 which is slidably mountedon member 68. This holder is provided with jaws 'H whose electrodeengaging surfaces are out of line with the electrodeengaging surface ofguide 61 and which cramp and hold the end of an electrode which has beenstressed by bending to bias its other end against said guide. Weldingcurrent is supplied through conductor 43, above referred to, to holder10 and thence to electrode 15.

'Electrode holder 10 is fed toward and away from electrode guide 61 by afeed rod 12 mechanically attached thereto but electrically insulatedtherefrom. This feed rod is engaged by feed rolls l2 of welding head H,and the motion thus applied to feed rod 12 is transferred to theelectrode I5 through holder 10. This holder is guided along member 88and is free to move relative thereto in the plane of the bent electrodein order to accommodate itself to the action of the bent electrode andthe resistance imposed thereto by feed rod 12. The feeding attachment ispositioned relative to the line of welding so that the plane of the bentelectrode is directed along the line of welding. Lateral movement of theelectrode relative to the line of welding is thus prevented.

By reason of the construction of the electrodeholding and guiding means,as shown in Fig. 8, movement of holder away from guide 81 withdraws thestub end of a used electrode l5 from guide 61, thus releasing thecramping force which held it in holder 10. The stub end is thus free todrop from the holder during its return movement to a loading positionsuch as illustrated in Fig. 5. The ease with which a new electrode maybe inserted in the feeding attachment and its self-ejecting nature arevery valuable characteristics to an operator who is thus enabled toperform more welding within a given period or" time. The electrodeguiding feature of this attachment also makes it possible to locate thearcing terminal of a stick electrode at a desired point of welding,which is of considerable importance when welding along an irregular seamsuch as at I8 of work I6.

The operation of the welding machine is determined by a limit switchcontrol forming the subject matter of my above referred to divisionalapplication Serial No. 406,388. Movement of feed rod 12 operates limitswitches which terminate welding operations initiated by the operatorand which return the electrode holder of the feeding attachment to itsloading position after the last welding operation of a series of weldingoperations capable of being performed with the same electrode.

As shown in Figs. 1. 5, and 6, these limit switches I3, 14, l5, l6 andTI are mounted through the agency of a tube 18 on welding head H. Thistube encloses feed rod 12 of the feeding attachment and a pin 19 on thisrod extends through a slot in the tube to engage and operate the limitswitches. These limit switches form part of a control circuitdiagrammatically illustrated in Fig. 9 for controlling the feed motor ofthe welding head in response to the travel of the electrode feedingattachment to supply measured lengths of electrode during each of aseries of welding operations after which the feeding attachment isreturned to its loading position for a new electrode. These switches maybe of any suitable type but are preferably snap actuated switches. Theyare operated by resilient arms 80 which are in the path of movement ofpin 19. This pin in its travel snaps by the ends of arms 80 of switches14 and 15 located intermediate the remaining switches. The relativespacing of the limit switches determines the measured lengths ofelectrode fed during each welding operation. This length of electrodecorresponds in the particular arrangement illustrated to that requiredfor welding seam 18 of float valve Hi.

In the control diagram of Fig. 9, the contacts of the various limitswitches have been identified by the same reference numerals applied tothe switch as a whole in Figs. 1, 5 and 6. These switches have beenillustrated in the positions they assume before being operated by pin isattached to feed rod 12 of the stick electrode feeding attachment. Theelectromagnetic relays and switches have been illustrated in theirdeenergized positions.

In Fig, 9 turntable H upon which the work is supported and electrodefeeding attachment [0 have been partially represented. The arc weldingelectrode held and guided by the feeding attachment is moved toward andaway from the work to strike and maintain a welding arc by the action ofthe welding head feed rolls B2 on feed rod 12 of the feeding attachmentit. These rolls are connected to and propelled by a feed motor 8|. Thespeed and direction of rotation of this feed motor is controlled inresponse to the voltage between the electrode and the work so thatfeeding attachment Iii driven thereby advances the electrode to and fromthe work to strike and maintain an arc of predetermined voltage. Thecontrol illustrated in Fig. 9 is of the valve circuit type embodyingelectric valves 82 and 83 and their control 84 which is connectedthrough conductors 85 to the arc welding electrode supported in feedingattachment l0 and to the turntable l'l upon which the work is supported.This control may .be that illustrated in United States Letters Patent2,175,017, William D. Cockrell granted October 3, 1939 and assigned tothe assignee of the present invention, in which case the electric valves82 and 83 shown in Fig. 9 correspond to electric valves 8 and l of thecircuit disclosed in said Letters Patent.

In Fig. 9 feed motor 8| may be started and stopped by the operatorthrough the agency of a start switch 86 and a stop switch Bl. Theclosure of switch 86 connects the operating winding 88 of relay 89across a source of alternating current supply 90. Relay 89 controlsthrough its contacts 9| the energization of the operating winding 92 ofrelay 93 and through its contacts 94 the energization of the operatingwinding 95 of the electromagnetic switch 96.

The operation of either relay 89 or relay 93 completes through theircontacts 9'! and 98 the connection of feed motor 8| through electricvalves 82 and 83 to the source of supply 98, When both of these relaysare deenergized, their contacts 91 and 98 complete a dynamic brakingcircuit for feed motor 8|. Relay 93 is also provided with contracts 9!]which are connected in shunt to the contacts of limit switch it.

Electromagnetic switch 96 controls the connection of terminals 42 and 43of the source of welding current and voltage to the welding electrodeand the work through circuits previously traced in describing thephysical structure of my machine. It is also provided with contacts itlwhich control the energization of travel motor 28 by connecting it to asource of supply H32. Contacts I03 of this electromagnetic switch are inshunt to resistor I94 which is connected in circuit with its operatingwinding 95.

The nature of the control circuit shown in Fig.9 will be betterunderstood from a consideration of its operation. When th stickelectrode feeding attachment I0 is in the position shown in Fig. 5,limit switch '13 will be open. Otherwise the various parts of the systemwill assume the positions illustrated.

When the operator closes start switch 88, winding 88 of relay 89 isconnected across the source of supply 90 through the contacts of thisstart switch and the contacts of stop switch 81. This relay willconsequently operate to close its contacts 94, open its contacts 9! andtransfer the connection through its lower set of contacts 91 to itsupper set of contacts Bl. The closure of contacts 94 of relay 89completes an energizing circuit for the operating winding 95 ofelectromagnetic switch 96 across the source of supply 90 throughresistance li'l i, limit switches M, iii and TI, and stop switch 32. Theclosure of these contacts also completes a holding circuit for theoperating windings 38 and of relay 89 and electromagnetic switch as fromthe righthand terminal of the source of supply 36 through limit switchesl4, l5 and T! and stop switch 81 to the left-hand terminal of the sourceoi supply 90. The closure of the upper set of contacts 91 of relay 89connects feed motor 8! across the source of ply 99 through electricvalve reduce the holding current below that required for pick-up.

It will thus be seen that by closing start switch 85, the source ofwelding current and voltage is applied to the electrode and the work,travel between the electrode and the work is instituted by energizingmotor 28 and feed motor Eli is subject to the control of $4 in responseto the voltage across the electrode and the work to feed the electrodetoward and from the work to strike and maintain a welding arc ofpredetermined voltage.

As the welding electrode is consumed during a welding operation thusinitiated, the feeding attachment Ill is fed toward the work andeventually limit switch 74 is opened by the engag ment of pin 79 of feedrod l2 with the operating arm 8i! of this limit switch. The opening oflimit switch 14 deenergizes the operating winding 83 of relay 89 and theoperating winding Q5 of electromagnetic switch 95. quently return to thepositions illustrated in Fig. 9 and thereby interrupt the supply ofwelding current and voltage to the electrode and work and deenergizetravel motor 523 and electrode feed motor 8!.

When the operator again closes start switch 8%, another weldingoperation is initiated. This operation continues until limit switch 15is opened by the travel of feed rod l2 attached to the electrode feedingattachment til. Thereafter, the operator by closing the start switch 86may institute a third welding operation which will continue until limitswitches 75 and H are operated by pin 19 on feed rod E2 of feedingattachment Ill. The operator must hold the start switch closed for thesecond and third welding operations until the holding circuit iscompleted by the respective closing of limit switches i l and 15.

The opening of limit switch ll interrupts the welding operation in themanners previously described. The operation of limit switch '16,however, completes an energizing circuit for operating winding 92 of therelay 93 from the righthand terminal of the source of supply 98 throughThey consecontacts 91' of relay 89 and limit switch 73 to the otherterminal of the source of supply 90. The closure of contacts 99 of relayQ3 completes a holding circuit for its operating winding around thecontacts of limit switch '16 and the transfer of connections from itslower contacts 93 to its upper contacts 98 completes the feed motorcircuit through electric valves 82' and 83 across the source of supplySll. Since the welding circuit has been opened at contacts Hill ofelectromagnetic switch 93, there will be no voltage between theelectrode and the work and control 84 for feed motor 8! will operate topropel the feeding attachment it away from the work until pin 79 on feedrod l2 eventually opens limit switch l3 whereupon the various parts ofthe control circuit of Fig. 9 return to the positions illustrated withthe exception, of course, of limit switch 13 which will be open.

It will thus be seen that the control illustrated functions to feedmeasured lengths of stick electrode during eachof a series of weldingoperations and then returns the feeding attachment to its loadingposition for the insertion of a new electrode. It is to be noted thatall this is accomplished through the agency of the control provided forthe electrode feed motor which consequently not only feeds attachment Hito strike and maintain a welding arc and to compensate for theconsumption of measured lengths of electrode but also after the totalconsumption of the electrode reaches a predetermined maximum returns thefeeding attachment to a loading position for the insertion of a newelectrode.

The control of Fig. 9 is enclosed within the cabinet Hi8 of the machineof which it forms a part as illustrated in Fig, 1 of the drawings. Acontrol board iiil' is also provided for adjusting the voltage of thewelding are, indicating the arc welding current and Voltage, adjustingthe speed of the travel motor and the like.

During welding, the operator is protected from the welding are by acylindrical enclosure Hi8 which is provided with a cover Hi5 rotatablysupported on rollers Hi). This cover is provided with a lightcontrolling window Ill through which the welding operator view thewelding operation when cover the completes enclosure 1%. The electrodefeeding attachment Ill extends through a slot at the lefthand end ofenclosure [$8.

In View of the description of the operations above given of the severalparts of my machine, the operation of the machine as a whole will not berestated here since it is obvious.

It is apparent that the many features of my invention above describedmay be variously modified without departing therefrom, and I aimconsequently in the appended claims to cover all such changes andmodifications which fall within the true spirit and scope thereof.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

l. Arc welding apparatus comprising a work holder having a cam surfacewhose configuration corresponds to a desired line of welding on the workand a work supporting surface which positions the line of welding on thework in registry with said cam surface, a support, a wheel tangentiallyengaging said cam surface and mounted for rotation on said support,means including said cam surface and said wheel for supporting andtraversing said work holder relative to a desired point of weldingdetermined by the tangential engagement of said cam surface and saidwheel, means for shifting the tangential engagement between said camsurface and said wheel about the axis of rotation of said wheel andthereby adjusting said point of welding and the slope of said line ofwelding at said point of welding relatively to said support, and meanson said support for feeding an electrode at a desired angle relativethereto and positioning its arcing terminal at said point of welding.

2. Arc welding apparatus comprising a support, a turntable having a camsurface parallel to and corresponding in configuration with a line ofwelding on a work part positioned relative thereto by the worksupporting surface of said turntable, means mounted on said support andengaging said cam surface for rotating and translating said turntablerelatively to said support in a plane parallel to a plane of weldingincluding said line of welding, means movable into and out of engagementtherewith for holding the work against the work supporting surface ofsaid turntable, means for mounting said last mentioned means on saidsupport so that its work engaging portion follows the rotary andtranslatory motions imparted to the work by said turntable, and meansfor feeding an electrode and positioning its arcing terminal in saidplane of welding op posite the line of welding on the work.

3. Arc Welding apparatus comprising a support,

a turntable having a cam surface parallel to and 5 corresponding inconfiguration with a line of welding on the work positioned relativethereto by the work supporting surface of said turntable, means mountedon said support and engaging said cam surface for rotating andtranslating said turntable relatively to said support in a planeparallel to a plane of welding including said line of welding, a memberadapted to engage the work and hold it on said turntable, a membermounted on said support, a ball and socket joint of rotation betweensaid members, a spring rod rotatably supported in one of said membersand attached to the other of said members for biasing them to apredetermined position relative to one another, means for moving saidmembers relatively to said support to force said work engaging memberagainst the work, and means for feeding an electrode and positioning itsarcing terminal in said plane of welding opposite the line of welding onthe work.

4. Welding apparatus comprising a work holder having a cam surface whoseconfiguration corresponds to a desired line of welding and a worksupporting surface which positions the line of welding on the work inregistry with said cam surface, a wheel tangentially engaging said camsurface, means including said cam surface and said wheel for supportingand traversing said work holder relatively to a desired point of weldingdetermined by the tangential. engagement of said cam surface and saidwheel, and means for shifting the tangential engagement between said camsurface and said wheel about the axis of rotation of said wheel andthereby adjusting the slope of said line of welding at said point ofWelding.

5. Welding apparatus comprising a work holder having a cam surface whoseconfiguration corresponds to a desired line of welding and a worksupporting surface which positions the line of welding on the work inregistry with said cam surface, means for supporting said holder forrotation and translation of said cam surface in a predetermined plane, awheel tangentially engaging said cam surface, means including said camsurface and said wheel for traversing said work holder relatively to adesired point of welding in the plane of said line of welding determinedby the tangential engagement of said cam surface and said wheel, andmeans for shifting the tangential engagement between said cam surfaceand said wheel about the axis of rotation of said wheel and therebyadjusting the slope of said line of welding at said point of Welding.

6. Welding apparatus comprising a turntable having a cam with a flangededge portion which is parallel to and corresponds in configuration witha line of welding on a work part positioned relative thereto by theconfiguration of the work supporting surface of said turntable, asupport, means for mounting said turntable for translation and rotationrelative to said support, a wheel tangentially engaging one side of saidflanged edge portion of said cam and mounted for axial rotation in saidsupport, means engaging the other side of said flanged edge portion ofsaid cam for pressing it into engagement with said wheel and therebydetermining the point of welding relative to said support, means foradjusting said last mentioned means about the axis of rotation of saidwheel and thereby adjusting said point of welding relatively to saidsupport, and

means for imparting axial rotation to said wheel.

'7. Welding apparatus comprising a support, a turntable mounted forrotation and translation relative to said support in a plane parallel toa plane of welding, a work holder mounted on said turntable and having aconfiguration for positioning the line of welding on a work part locatedthereon in said plane of welding, a cam attached to said turntable andhaving a flanged edge porion whose configuration corresponds to saidpredetermined line of welding, means including a pair of wheels mountedon said support and located on opposite sides of said flanged edgeportion of said cam for determining the point of welding relative tosaid support, means for pressing said wheels toward one another intoengagement with the opposite sides of said flanged edge portion of saidcam, means for imparting rotation to at least one of said wheels, andmeans for bodily rotating one of said wheels about the axis of rotationof the other of said wheels and thereby adjusting their point ofengagement with said flanged edge portion of said cam and said point ofwelding relatively to said support.

8. Welding apparatus comprising a turntable having a cam with a flangededge portion which is parallel to and corresponds in configuration witha line of welding on a work part positioned relative thereto by theconfiguration of the work supporting surface of said turntable, asupport, means for mounting said turntable on said support for rotationand translation in a plane parallel to a plane of welding including saidline of welding, said means including a wheel tangentially engaging oneside of said flanged edge portion of said cam and mounted for axialrotation on said support, means for imparting axial rotation to saidwheel, and means mounted on said support and engaging the other side ofsaid flanged edge portion of said cam for pressing it into engagementwith said wheel and thereby determining the point of welding in saidline of welding.

9. Welding apparatus comprising a turntable having a cam with a flangededge portion which is parallel to and corresponds in configuration witha line of welding on a work part positioned relative thereto by theconfiguration of the work supporting surface of said turntable, asupport, means for mounting said turntable on said support for rotationand translation in a plane parallel to a plane of welding including saidline of welding, said means including a pair of wheels mounted for axialrotation on said support located on opposite sides of said flanged edgeportion of said cam, means including a flange and groove connectionbetween one of said wheels and said flanged edge portion of said cam forholding said flanged edge portion of said cam between said wheels, meansfor pressing said wheels toward one another into engagement with theopposite sides of said flanged edge portion of said cam and therebydetermining the point of welding in said line of welding, and means forimparting axial rotation to at least one of said wheels.

10. Welding apparatus comprising a turntable having a cam with a flangededge portion which is parallel to and corresponds in configuration witha line of welding on a work part positioned relative thereto by theconfiguration of the work supporting surface of said turntable, asupport, means including a plurality of balls mounted on said supportand engaging said turntable for guiding said turntable relatively tosaid support, means for mounting said turntable on said support forrotation and translation in a plane parallel to a plane of weldingincluding said line of welding, said means including a wheeltangentially engaging one side of said flanged edge portion of said camand mounted for axial rotation on said support, means for impartingaxial rotation to said wheel, and means mounted on said support andengaging the other side of said flanged edge portion of said cam forpressing it into engagement with said wheel and thereby determining thepoint of welding in said line of welding.

VERNI J. CHAPMAN.

